The Physics of Throwing a Football

by
WILLIAM MACHIN Sept. 11, 2017

William Machin

William Machin began work in construction at the age of 15, while still in high school. In 35 years, he's gained expertise in all phases of residential construction, retrofit and remodeling. His hobbies include horses, motorcycles, road racing and sport fishing. He studied architecture at Taft Junior College.

man about to throw football
Photo Credit: Purestock/Purestock/Getty Images

Discussions on the subject of throwing a football are as common as chalk lines on a football field. Coaches and players talk about the proper grip, footwork and throwing motion, but few discussions mention of the physics involved. Prolific passers rely on the physics associated with the shape and design of a football when planning throws.

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Aerodynamics

Footballs have been described as inflated leather missiles with laces, eggs and pointed ends. The shape of a football is such that it allows the ball to be thrown in ways that set the game apart from other ball games. Newton’s first law of motion explains that an object at rest remains at rest unless acted upon by an external force. In this regard, a passer’s throwing motion becomes the external force that propels the football. But it wouldn’t travel as far if the passer attempted to throw the football with the points of the ball perpendicular to the line of travel. In addition to throwing the ball point first, the passer’s grip and release cause the ball to spin on its lateral axis, and he benefits from the aerodynamics of the ball’s ellipsoid shape.

Short and Long Passes

Common sense suggests that the amount of force differs when throwing short and long passes. This is not to say a passer might not attempt to zip the ball between two defenders when his receiver is running a short pass pattern. But overall, less force is needed to throw a 15-yard pass and more is needed to throw a 40-yard pass. Newton’s laws of gravity explains that every action is accompanied by an equal and opposite reaction. This helps you understand why most short passes have less loft and arc than long passes. Typically, passers focus on the receiver when throwing short patterns. If you watch a replay or stand near a quarterback who is throwing a long pass, you’ll notice his eyes are focused on a point at the top of a perceived arc when he releases the ball. Whether openly stated or not, passers understand the physics that pertain to an equal and opposite reaction when throwing a football.

Types of Footballs

Comparing footballs used in youth leagues with regulation professional footballs, you see that youth footballs have a greater circumference. The reason for this is associated with the average strength of the players at each level. A ball with a grater circumference holds a greater volume of air and as a result, carries farther when thrown. Footballs used at the collegiate level have a larger circumference than youth footballs and are slightly smaller than professional footballs. By the time passers become professionals, they can throw a regulation football short or long without the aid of additional air volume.

Observations

Physics applies to every aspect of throwing the football, from a passer’s throwing motion to the distance and accuracy of his passes. Hall of Fame quarterbacks, such as Johnny Unitas and Joe Montana, used the physics of throwing a football to an advantage. Both understood that releasing the ball a certain way caused it to react a certain way. You can realize the physics involved by throwing a football the length of a garden bench and throwing it to a neighbor across the street. Renowned physicist Sir Isaac Newton formulated the laws of gravity and motion that apply each time you throw a football.